Gum inhibitor



I Patented Feb. 11, 1941 I UNITED STATES PATENT OFFICE GUM INHIBITORAugustine F. S. Musante, Media, and John Harold Perrine, Prospect Park,Pa., assignors to Sun Oil Company, Philadelphia, Pa., a corporation ofNew Jersey No Drawing. Application August 22, 1939,

Serial No. 291,326

Claims. 01. 44-9 The object of the invention is to improve hybeenincreased 200 minutes nearly always prove drocarbon'oil, andparticularly gasoline and more stable in storage for more than a year,the lack especially gasoline produced by cracking a highof a precise, asdistinguished from an approxier boiling petroleum fraction, bypreventing the mate, relationship between increase in the in- 5formation of gum during storage for a prolonged duction period andstorage stability makes it period of time. It is well known that inordinary highly desirable that the increase in the inducgasoline,formation of gum proceeds slowly for a tion period should considerablyexceed 200 time, after which the rate of formation increases minutes. isuddenly and proceeds rapidly. It is also well We have found that theaddition to'gasoline known that gum formation may be retarded and of thereaction product of trichlorpropane+ 10 even substantially prevented bythe addition of p-phenylenediamine will increase the induction variousorganic compounds. Many of such comperiod to approximately from eight tofifteen pounds, however, are objectionable because they hours. arerelatively soluble in water, or' because they When symmetricaltrichlorpropane is reacted are soluble only with difilculty in gasoline,or with p-phenylenediamine the hydrochloride of 15 because theirrelative solubility in water and three different products may beobtained,'degasoline is not of the character hereinafter expending uponthe number of moles of each prodplained as necessary. Many others havedefinite uct react I and even substantial gum-inhibiting properties,Thus, if one mole of trichlorpropane is reacted but areeifective only inretarding the rate of gum w t on m l of prph ny ed a ine thereacformation or of prolonging for an insuflicient tion'is rep e e d y efOllOWlng equation! time the limited period during which the rate C3H5C13+H2N'C6H4 NH2 glfoium formation in untreated gasoline may be ICQIBEIMINEGHSNHLHCI In th present highly developed t t of t If one moleof trichlorpropane is reacted with 25 art no gum inhibitor can be deemedsatisfacto two moles of p-phenylenediamine the reaction is unless thetreated gasoline in storage will reas v main stable for a long period oftime approxi-' C3H5 13+2H2N C6H4 m maimg (say) and .unless the gumCaH5.CI.(I-II\T.CeH5.NI-I2.HCI)2 hibitor possesses the water-011solubility characteristics hereinafter explained; and the inhibitor If omole of trichlvrpropene is reacted with '.must be reasonable in cost andeffective when three moles of D-P y m all O e added in very smallproportion, and must have chlorine atoms are removed from the trichlornocharacteristics that for other reasons would propane and a residue ofp-phenylenediamine make its use objectionable]; t u m takes their place.Thusf I Different methods are nown for es ng e resistance of gasoline togum formation in stor- E; (HN C H m H01) age without actually storingthe same. The most 3 nearly reliable of such tests is generally deemedDepending on the number of moles of to be the bomb induction test,described by p-phenylenediamine which are reacted with one Winning &Thomas. Industrial and Engineering mole of symmetrical trichlorpropane,we obtain 40 Chemistry, Vol. 25, 1933, page 511. By this test thydrochlorides f; the so-called induction periods of the untreatedCmHNCGH NH, t and treated gasoline are ascertained. The increase in theinduction period bears a relation 7 45 to storage stability. While suchrelation is-not HaCl so nearly invariable as to enable storage stabilityto be accurately calculated therefrom. a great fi increase in theinduction period indicates storage a H.uN.c.H4.NH= 5o stability for aprolonged period. While some I a o gasolines in which the inductionperiods have or t been increased by the use of an inhibitor byCH:.HN.C;H4.NH1 minutes have proved stable in storage for as longCHEN-Gama.

as a year, and while'gasolines in which the origi- 65 119.1 inductionperiods of treated gasolineshave v 55 These hydrochlorides are obtainedby reacting the two products, symmetrical trichlorpropane andP-phcnylenediamine, either under pressure or by long refluxing. Thehydrochlorides are broken down to the free base by means of a ratherconcentrated solution of caustic soda. The solid free base is thenthoroughly washed with water, in order to remove the excess caustic sodaand the salt. It is then dried.

The unreacted trlchlorpropane and the unreacted-p-phenylenediamine areremoved by treatment with acetone, and the residue, containing the freebase or bases, is finally extracted with alcohol. The alcoholic extractcontains one or more of the'free bases referred to. The alcohol isevaporated and the free base or bases used as such as gum inhibitors.

' The light-colored product,

- C3H5.C12.HN.C0H4.NH2, has a melting point of 135 C. It is insoluble inwater and in carbon tetrachloride, slightly soluble in benzene, andreadilysoluble in alcohol. 0.0384

grams is dissolved by 100 cc. of gasoline at 20 C. If previously wetwith alcohol, 0.0994 grams is dissolved by 100 cc. of gasoline at 20 C.

In concentrations of 0.03 percent, in gasoline, the following inductionperiods were observed.

Induction period Induction period of gasoline+0.03 Increase in inductionperiod of raw gasoline percent of above due to inhibitor gum inhibitor3% hours 18% hours 14% hours (885 minutes).

The product CaH5.C1(I-IN.CeH4.NI-I2)2 has a melting point of 80 C. It isinsoluble in-water,

carbon tetrachloride and benzene, readily soluble in alcohol, andslightly soluble in gasoline. Only 0.0225 grams of this product isdissolved by 100 cc. of gasoline. If the sample is previously wet withalcohol 0.1016 grams is dissolved by100 cc. of gasoline.

In' concentrations of 0.03 percent, in gasoline, the following"induction periods were observed:

Induction period oi gasoline+0.03 percent of above gum inhibitorInduction period Increase in induction period of raw gasoline inhibitordue to 3% hours 16% hours 12% hours (750 minutes).

Induction period Induction period of gasoline-+0.03 Increase ininduction period of raw gasoline percent of above due to inhibitor guminhibitor 3% hours l2 hours 8% hours (495 minutes) It is to be observedthat each of the above- The induction period was measured in two 50 cc.bombs of the character of that disclosed in the Winning and Thomaspublication above referred to. The bombs were heated in a steam bath,the steam being generated in the bath by I an electric heater. The-bathswere provided with a constant level water feed. The end of the inductionperiod was taken at the point where the pressure curve dropped sharply.The pressures were recorded on charts. The concentration of the addedinhibitor to the gasoline was 0.03 per cent. by weight. The inductionperiod of the raw gasoline (which was that produced by a known thermalcracking process) was found to be about three and three quarters hours,while the induction periods of the same gasoline with the inhibitorsadded varied from twelve hours to eighteen hours and thirty minutes,giving increased induction periods varying from eight hours and fifteenminutes tofourteen hours and forty-five minutes.

The concentration above specified was chosen in the experimental testsas a matter of convenience; that is, the time for each test wasreasonable in length, the magnitude of the effect was easily detected,and all of the observations could be readily compared. There is noobjection to any higher concentration except that of cost, and a verymuch lower concentration is believed to be effective in the case of allgasolines. With some gasolines, a much reduced concentration down to aslow as .001 per cent. gives an increase in the induction periodsufficient to insure stability on storage for the maximum length of timeduring which finished gasoline is usually stored. Further, the preferredconcentration will vary with the induction period of the untreatedgasoline, which may vary from 1 V2 to 4 hours or within even widerlimits. In the case of untreated gasoline having a low induction perioda higher concentrationof the inhibitor is required, in order to insurethe desired storage stability, than with untreated gasoline having ahigher induction period.

An advantageous, and indeed practically necessary, characteristic of aninhibitor is that it shall be relatively soluble in gasoline andrelatively insoluble in water; that is, when an inhibitor is soluble inboth'water and gasoline it is essential that the partition ratio withwater be low.

It is convenient to dissolve the inhibitor in a relatively small amountof a mutual solvent, such as alcohol,'in a concentration much in excessof that desired and then add the solution to such large amount ofgasoline as will give the desired concentration.

The raw gasoline to which the inhibitor was added in the above exampleis typical in that it contains oxidation inhibitors (usually of aphenolic nature), as evidenced by the substantial induction period shownby the tests. Such gasoline has the characteristic hereinbeforementioned of preventing oxidation until the natural inhibitors becomeoxidized, after which the gasoline starts to oxidize rapidly. It isdesirable, therefore, that the raw gasoline should be subjected to nopre-treatment, such as any treatment that would involve the addition ofperoxides, that would destroy the natural inhibitors. However, theinhibitor is operative without, as well as with, the natural inhibitorsin gasoline.

The standard boiling range and other characteristics of the fraction ofpetroleum known as-gasoline is not constant but varies from time aasaseato time withimproved methods of refining and with improvements ininternal combustion vengi'nes; but the inhibitor is equally eflicientwhen added to any petroleum fraction whose boiling range and othercharacteristics so nearly approximate contemporary standards that it maybe substituted therefor in internal combustion engines and for otherknown uses. The inhibitor is eflicient also as applied to other motorfuels and to other petroleum distillates and liquid hydrocarbons.

What we claim and desire to protect by Letters Patent is:

1. A petroleum hydrocarbon composition resistant to gum formationcomprising a petroleum hydrocarbon that on storage will form gum, towhich has been added a small percentage of the reaction product oftrichlorpropane p-phenylenediamine.

2. A gasoline composition resistant gum formation comprising gasolinethat on storage will form gum, to which has been added a smallperpropane+p-phenylenediamine.

3; A motor fuel resistant to gum formation comprising a hydrocarbonmotor fuel that on storage will form gum, to which has been added asmall percentage of the reaction product oftrichlorpropane+p-phenylenediamine.

4. The process of inhibiting gum formation in gasoline, petroleumdistillates and other liquid hydrocarbons that on storage will form gum,which comprises added thereto a small percentage of the reaction productof trichlorpropane-l-p-phenylenediamine.

5. The process of inhibiting gum formation in gasoline and otherhydrocarbon motor fuels that on storage will form gum, which comprisesreacting trichlorpropane and p-phenylenediamine, breaking down thehydrochlorides and removing unreacted trichlorpropane andpphenylenediamine, leaving a residue containing the free base or bases,extracting the same with alcohol and adding the free base or bases tothe said hydrocarbon.

AUGUSTINE 'F. S. MUSANTE. JOHN HAROLD PERRINE.

